Method and apparatus for discharging a controlled amount of cryogen onto work surfaces in a cold roll mill

ABSTRACT

The present invention is directed to a method and apparatus for adjusting the amount of cryogen delivered to a mill stand ( 1 ) using a non-optical sensor ( 16   a ) to measure at least one operating parameter selected from the group consisting of roll stand parameters, rolled product parameters, and cryogen parameters. Output signals, are generated by the non-optical sensor and a controller ( 17 ) calculates numeric values based on the signals. When the calculated numeric values reach a predetermined set point value that correlates with mill stand temperature, the flow of cryogen is adjusted to disperse a desired amount of cryogenic fluid to said mill stand ( 1 ) to control rolling temperature.

CROSS REFERENCE TO RELATED APPLICATION

This application is the National Stage of International Application No.PCT/US08/74451, filed Aug. 27, 2008, which claims the benefit of U.S.Provisional Application No. 60/968,479, filed Aug. 28, 2007, which isincorporated herein by reference in its entirety as if fully set forth.

BACKGROUND

The present invention is directed to a method and apparatus forcontrolling the amount of cryogenic coolant applied to the work rolls,roll gap, or rolled product in a mill stand during a cold rollingoperation. The amount of cryogen is adjusted in response to a sensoroutput signal indicative of any one or combination of measured operatingparameters including mill stand parameters, rolled product parameters,ambient atmosphere conditions and cryogen parameters.

Cold rolling is a process used to produce metallic sheet, strip orprofiles with specific mechanical properties such as surface finish andspecific dimensions within certain dimensional tolerances. In a coldrolling operation, the sheet or strip passes between twocounter-rotating work rolls adjusted at a predetermined roll gap settingso that the rolled product is plastically deformed to a requiredthickness defined by the set roll gap. Cold rolling generates heat inresponse to the forces required to deform the strip and in response tofriction between the work rolls and the strip. The generated heataccumulates in both the work rolls and, if not controlled, may result intemperatures above acceptable cold rolling levels. The acceptabletemperatures can vary based on type of metal, strip dimensions, coldrolling parameters and surface finish. Excessive rolling temperaturesmay lead to (i) changes in the rolled product properties such as surfaceoxidation, (ii) defects in the strip surface due to the strip adheringto heated roll surfaces and (iii) oxidation of working rolls. Suchproblems reduce surface quality.

Past attempts to prevent excessive heat build-up in the mill stand andto reduce friction between the work rolls and the strip include floodingthe work rolls and product with coolants and lubricants such as oil,water, or emulsions. However, many of the liquids have negative effectsif not quickly removed from the finished product surface. For example,if the metal being cold-rolled is steel, water or aqueous emulsionremaining on the strip can cause oxidation, or rust. In addition,removing oily residue increases production cost and createsenvironmental problems. For high quality surface finishes, dry rollingis sometimes used to avoid having to deal with the above-mentionedproblems. Rolling dry is also sometimes chosen because it will impart abrighter (shinier) finish onto the rolled strip. When rolling dry,production speed must be limited in order to avoid excessive heat buildup. In yet other cases, a type of minimum quantity lubrication is usedto reduce friction. Even with minimum quantity lubrication, however, inorder to maintain the production of strip with good surface finish, itis often necessary to stop the mill rolling to perform periodic cleaningof the working rolls to remove accumulated build-up.

Recent efforts to find alternative coolants or cleaning methods have ledto the use of an inert gas at a lower temperature than the temperatureof the rolled product passing through the roll gap. The inert gas may bein either gaseous or liquid form, i.e. a cryogen, or mixed-phase. Thelower temperature inert gas provides a cooling alternative to oil,water, or emulsion coolants. Since there is no liquid residue left onthe strip when inert gas is used as a coolant in a rolling operation,corrosion problems associated with residual water or emulsion remainingon the strip are prevented. Moreover, use of inert gas provides acleaning effect for the working rolls and strip surface which, amongother benefits, extends the service life of working rolls.

In applications where a cryogenic coolant is used, overcooling andundercooling are significant issues because of the larger temperaturedifferential between the rolled product and the cryogen. There have beenefforts to adjust cryogenic coolant flow rates based on temperaturemeasurements from the roll surface. The temperature measurements aretypically taken, however, using optical pyrometers located on the stripentry side of the roll stand, and the flow of cryogenic is controlled tokeep the mill temperature within a specified range.

This approach is problematic because using optical means to measure atemperature change at typical cold rolling temperature ranges isdifficult and unreliable. The work rolls are curved or crowned and arehighly reflective, providing low and uncertain emissivity for opticalpyrometer measurements. In addition, any reflections from extraneouslighting will affect the optical readings within the normal cold rollingtemperature range. Condensation caused by the cryogen cooling the air inthe space between the optical pyrometer and work roll surface can alsocause inaccurate temperature readings.

Substituting thermal contact sensors for the optical pyrometers is notpractical. Measuring work roll surface temperature with contact sensorsis difficult to implement and such contact measurements are prone to beunreliable. Use of internal thermocouples to measure work roll surfacetemperature has been suggested, but would also be unreliable anddifficult to implement. For example, positioning internal thermocouplesnear the work roll surface is complex from an engineering viewpoint,difficult to achieve, and expensive. Installation of such thermocouplescould be simplified by positioning them deeper within the roll, i.e.positioned at a greater distance from the roll surface. However, deeplyimbedded thermocouples will lead to an impaired response that generatesan inadequate signal for good cooling control.

In addition to the temperature measurement deficiencies of the priorart, accurate, real-time adjustment of the flow rate of a cryogeniccoolant using conventional methods is also problematic.

Therefore, the cryogen cooling control apparatus disclosed in the priorart is impractical and not capable of delivering an accurate, controlledamount of cryogen to a cold roll mill stand. Accordingly, there is awidely-felt need in the industry to provide a cryogen delivery systemthat provides improved temperature measurement in combination withimproved accuracy in the mass flow rate of cryogen delivered to a coldroll mill stand.

Examples of prior art in this field include German Patent No. DE 199 53280, PCT Publication No. WO 2006/074,875A1, and U.S. Pat. No. 6,675,622.

SUMMARY OF THE INVENTION

In one respect, the invention comprises a method including measuring atleast one operating parameter of a cold rolling process, each of the atleast one operating parameter being correlated to the thermal conditionsof an element of the cold rolling process, and controlling operation ofa cryogenic cooling device based at least in part on measurements of theat least one operating parameter.

In another respect, the invention comprises an apparatus for use with acold rolling process having at least one sensor, each of the at leastone sensors being adapted to measure an operating parameter of the coldrolling process, the operating parameter being correlated to the thermalconditions of an element of the cold rolling process. The apparatus alsoincludes a cryogenic cooling device having an adjustable dischargeintensity, and a controller that is configured to receive output signalsreceived from the at least one sensor and is programmed to adjust thedischarge intensity of the cryogenic cooling device based at least onpart on the output signals received from the at least one sensor.

In yet another respect, the invention comprises a method comprisingmeasuring a load force acting on a roll of a cold rolling process andcontrolling operation of a cryogenic cooling device based at least inpart on measurements of the load force.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D show various sensors positioned to measure mill standparameters;

FIG. 1E shows a combination of at least two different sensors positionedto measure mill stand parameters;

FIGS. 2A-2D show various sensors positioned to measure rolled productparameters;

FIG. 2E shows a combination of at least two different sensors positionedto measure rolled product parameters;

FIGS. 3A-3B show various sensors positioned to measure cryogenparameters;

FIG. 3C shows a combination of at least two different sensors positionedto measure cryogen parameters;

FIG. 4A shows sensors positioned to measure mill stand parameters incombination with sensors positioned to measure rolled productparameters; and

FIG. 4B shows a combination of sensors positioned to measure mill standparameters, sensors positioned to measure rolled product parameters, andsensors positioned to measure cryogen parameters.

DETAILED DESCRIPTION OF THE INVENTION

The use of cryogenic coolants, namely liquid nitrogen or other suitableliquefied or solid gas, eliminates problems associated with earliercoolants such as water, oil, and emulsions. However, cryogens are alsoproblematic in that it is essential to maintain accurate control overthe amount of cryogen delivered to the work roll surfaces and rolledproduct surfaces (hereinafter referred to as working surfaces), so thatunder-cooling or over-cooling is avoided. In the past, water-based andoily coolants were simply flooded into the region of the roll gap andthe over-supply of coolant provided a self-regulating, steady-statethermal condition in the work surfaces, producing desired properties inthe final rolled product.

When the coolant is a cryogen, however, it is not possible toself-regulate work surface temperature by flooding with an over-supplyof coolant because excess amounts of cryogen will create uncontrolledoperating conditions. For example, excess amounts of cryogen createlarge vapor clouds that obscure visibility in the mill stand, andpossible oxygen deficient atmospheres within the mill operating area. Inaddition, over-cooling adversely affects finished product quality due toa reduction in the plasticity of the rolled product. Over-cooling alsoproduces excessive amounts of condensation on the sheet or stripsurfaces creating surface defects or corrosion problems. Therefore,accurate control over the amount of cryogen delivered to the mill standis essential to avoid the above problems.

As explained above, however, existing attempts to base cryogenic flowrates on temperature readings taken by pyrometers has proven inaccurateand impractical. The present invention utilizes operating parametersother than direct temperature measurements of the surface of the rolledmaterial, individually and/or in combination, to determine desiredcryogen flow rates. Many of the measured parameters are correlated tothe temperature of the rolled material. It should be understood thatparameters that are correlated to the temperature of the rolled materialexclude direct measurement of the temperature of the rolled material.

As used herein, the term “cryogenic cooling device” is intended to meanany type of apparatus or device which is designed to discharge or spraya cryogenic fluid (either in liquid, mixed-phase, or gaseous form).Examples of cryogenic cooling devices include, but are not limited to,cryogenic spray bars, individual cryogenic spray nozzles, and devicescontaining arrays of cryogenic spray nozzles.

Referring to FIGS. 1A through 1D, various cryogen delivery systems 10 afor a mill stand 1 are shown. Each cryogen delivery system 10 acomprises a different sensor positioned at a suitable location formeasuring operating parameters for the cold rolling process. In eachembodiment, mill stand 1 includes a pair of opposed work rolls 2 a and 2b set to a predetermined roll gap 3, preferable but not necessary backuprolls 4 a and 4 b that maintain a constant distributed roll force on thework rolls and rolled product 5 and a strip entry side 6 that receivesincoming product.

Referring to FIG. 1A, the cryogen delivery system 10 a includes astorage tank 11 that contains a supply of cryogen such as liquidnitrogen or other liquefied gas at a temperature of −70° C. or lower. Inthe preferred embodiments, the pipe or conduit 12 is attached to storagetank 11 and conduit 12 includes a first remote end 13 a and a secondremote end 13 b proximate the strip entry side 6 of the mill stand. Eachremote end 13 a and 13 b includes a cryogenic cooling device 14 a and 14b that extends across the width of the mill stand or strip at a locationsuitable for disbursing a controlled amount of cryogen onto the worksurfaces of mill stand 1. In some applications, each remote end 13 a and13 b is placed at the strip outlet of the roll gap 3 to improve cleaningeffects. Although the cryogen delivery system is described as comprisingcryogenic cooling devices 14 a and 14 b, it should be understood thatany device suitable for discharging a controlled amount of cryogen ontothe work surfaces may be used. For example, a cryogenic spray bar havingan elongated discharge slot that extends across the mill stand width orstrip width or a device having an array of individually controllednozzles could be used.

In the embodiment shown in FIG. 1A, a mill screw 15 that adjusts themill gap includes a load cell 16 a. The mill screw 15 is operated toproduce a mill gap required to produce a metallic sheet or strip havingpredetermined mechanical properties, surface finish, and dimensions, andload cell 16 a generates continuous output signals indicative of theroll force. Load cell 16 a is connected to a controller 17, for example,a programmable logic controller (PLC) that operates a control valve 18fitted within conduit 12 at a location between storage tank 11 and thecryogenic cooling devices 14 a and 14 b. The controller 17 records theoutput signals from load cell 16 a.

Alternatively, a load cell 16 b may be positioned to measure roll forceon a bearing 19 that supports the lower backup roll 4 b. Similar to loadcell 16 a, load cell 16 b is connected to controller 17, which recordsthe incoming stream of data from load cell 16 b.

The numeric values from load cell 16 a and/or 16 b are used to determinewhen control valve 18 should be operated to regulate the mass flow ofcryogen from storage tank 11 to mill stand 1, and as implied, cryogendelivery system 10 a may include more than one load cell, for example,but not limited to, load cells 16 a and 16 b whereby controller 17 isprogrammed to provide averaged numeric values based on a continuousincoming stream of data from multiple load cell measurements.

Because roll force can be correlated with the thermal conditionsexisting in the roll stand, and because roll force is influenced byrolling temperature, the roll force measurements are used as feedbacksignals to accurately regulate the flow of cryogen within a desired massflow range or at a desired mass flow set point. Accordingly, thedischarge intensity of cryogen dispersed onto the work surfaces, or intothe roll gap, is controlled in response to the numeric values from theload cell measurements. For example, when the numeric values indicatethat the measured roll force is about 15% higher than the roll forceabsent any cryogen, controller 17 transmits a signal that operatescontrol valve 18 to reduce the mass flow rate of cryogen sprayed ordispersed onto the work surfaces or roll gap until the numeric valuesreturn to the preferred range. The adjusted mass flow of cryogencontrols the roll force, and thereby regulates rolling temperatures inthe mill stand.

As an alternative to any of the control valves described herein, athrottling gas system could be used to control the mass flow of cryogen.An example of a throttling gas system is provided in U.S. patentapplication Ser. No. 11/846,116, filed Aug. 28, 2007, which isincorporated herein by reference as if fully set forth. In a cryogeniccooling device that does not use a throttling gas, the dischargeintensity of the cooling device is primary a function of the flow rateof cryogen through the cryogenic cooling device. In a cryogenic coolingdevice that does uses a throttling gas to control discharge intensity,the discharge intensity of the cooling device is a function of both theflow rate of cryogen and throttling gas through the cryogenic coolingdevice.

Referring to FIG. 1B, in this embodiment, the cryogen delivery system 10a is adapted to measure stress conditions on the work roll surface tocontrol the flow of cryogen to the mill stand 1. Cryogenic sprayquenching is known to give the effect of causing residual compressivestress conditions on the quenched surfaces. In this embodiment, one ormore X-ray analyzers 20 a and 20 b, capable of determining the stressconditions in the surface of the work rolls 2 a, 2 b, are used toindicate the amount of stress occurring during the cold rollingoperation.

Output signals indicative of residual stress are generated by analyzers20 a and 20 b, and the signals are received as a continuous stream ofdata by controller 17. Similar to the above roll force measurements,controller 17 uses the numeric values from the incoming stream of datafrom the analyzers 20 a and 20 b and operates one or more control valves18 and 18 a in response to a set point value that correlates with atargeted measured stress which, in turn, correlates with desiredtemperature conditions in mill stand 1 so that the mass flow of liquidnitrogen from storage tank 11 to cryogenic cooling devices 14 a and 14 bis regulated to disperse a controlled amount of cryogen onto the worksurfaces.

In the present embodiment, shown in FIG. 1B, two control valves 18 and18 a are provided. Each control valve communicates with controller 17 sothat the cryogen spray from cryogenic cooling devices 14 a and 14 b canbe individually regulated. In addition, as described above, the numericvalues can reflect an average of the incoming stream of multiple stressmeasurements (from multiple x-ray analyzers) to improve accuracy.

In FIG. 1C, at least one sensor 21 a and/or 21 b is provided in thecryogen delivery system 10 a to measure electrical resistance in thework rolls 2 a and 2 b. Sensors 21 a and/or 21 b can be Ohm meters orany other suitable device known in the art for measuring electricalresistance, and similar to before, the sensors 21 a and 21 b generateoutput signals indicative of electrical resistance of the work rolls.Controller 17 receives the incoming stream of data and operates at leastone control valve 18 in response to a set point value so that cryogeniccooling devices 14 a and 14 b disperse a desired controlled amount ofcryogen from storage tank 11 onto the work surfaces. The numeric valuesof the work roll resistance correlate with electrical resistanceconditions on the roll which, in turn, correlate with the temperatureconditions in mill stand 1, and the numeric values can either comprisean average of the data transmitted from sensors 21 a and 21 b or a valuebased on a single sensor, either 21 a or 21 b.

Referring to FIG. 1D, at least one sensor 22 a and/or 22 b is providedin the cryogen delivery system 10 a to measure mill speed, for example,the speed of the rotating work rolls 2 a and 2 b and/or the travelingspeed of the rolled product. Sensors 22 a and/or 22 b may comprisetachometers or any other suitable measuring device known in the art, andsimilar to before, the sensors 22 a and 22 b generate output signalsindicative of the mill speed. Controller 17 receives the incoming streamof data, and in response to a set point value, operate control valves 18and 18 a so that cryogenic cooling devices 14 a and 14 b disperse adesired controlled amount of cryogen from storage tank 11 onto the worksurfaces.

In the instance of mill speed measurements, the measured numeric valuesdo not correlate with the temperature conditions in mill stand 1.However, mill speed correlates directly with mill throughput. Therefore,cryogen flow from storage tank 11 to cryogenic cooling devices 14 a and14 b can be ratioed, or proportioned/controlled to mill speed in eithera directly linear, or even a more complex, empirically-derived function.In addition, the numeric values can either comprise an averaged orindividual value based on the data transmitted from multiple sensors,such as sensors 22 a and 22 b.

Referring to FIG. 1E, sensors that measure different operatingparameters are combined in cryogen delivery system 10 a to improveaccuracy in rolling temperature control. The delivery system includesboth X-ray analyzers 20 a and 20 b to measure residual roll stress andsensors 22 a and 22 b to measure mill speed. The output signalsgenerated by the different sensors are transmitted to controller 17which is programmed to combine the incoming stream of data intocalculated numeric values. When the calculated value corresponds with aset point value, the controller 17 transmits a signal that operates atleast one control valve 18 and/or 18 a and a controlled mass flow ofcryogen is delivered from storage tank to cryogenic cooling devices 14 aand 14 b and dispersed onto the work surfaces of mill stand 1.

Referring to FIGS. 2A through 2D, the drawings show examples of cryogendelivery systems 10 b where each cryogen delivery system 10 b has adifferent non-optical sensor positioned at suitable locations formeasuring rolled product parameters. In this set of embodiments, millstand 1 includes work rolls 2 a and 2 b, a roll gap 3, preferable butnot necessary backup rolls 4 a and 4 b, and a strip entry side 6 forreceiving the rolled product 5.

Referring to FIG. 2A, the cryogen delivery system 10 b is similar to thecryogen stand delivery system 10 a, and includes storage tank 11containing a cryogen such as liquid nitrogen or the like, conduit 12extending to remote ends 13 a and 13 b proximate the strip entry side 6,and cryogenic cooling devices 14 a and 14 b. In some applications, theremote ends 13 a and 13 b are on the strip outlet to improve cleaningeffects. However, in this embodiment, cryogen delivery system 10 bincludes at least one non-optical sensor that generates an output signalindicative of temperature in the rolled metallic sheet or strip. In thisembodiment, the sensors are thermocouples 23 a and 23 b, however, anysuitable, non-optical temperature measuring device known in the art maybe used without departing from the scope of the present invention.Controller 17 receives the continuous incoming stream of data fromthermocouples 23 a and 23 b, and is programmed to respond a set pointvalue by transmitting a signal that operates at least one control valve18 so that cryogenic cooling devices 14 a and 14 b receive and dispersea controlled mass flow of cryogen from storage tank 11 onto the worksurfaces in mill stand 1.

Referring to FIG. 2B, in this embodiment, the cryogen delivery system 10b measures stress conditions in the surface of the rolled metallic sheetor rolled product 5 to provide a desired mass flow of cryogen to millstand 1. As mentioned above, cryogenic spray quenching is known to givethe effect of causing residual compressive stress conditions on thequenched surfaces. Therefore, one or more X-ray analyzers 24 a and 24 b,capable of determining the stress conditions in the rolled productsurface, are positioned on the exit side 6 a of the mill stand toindicate the amount of stress that is occurring in rolled product 5during cold rolling. Output signals indicative of residual stress in therolled product are generated by analyzers 24 a and 24 b, and the signalsare transmitted as a continuous stream of data to controller 17. Similarto the above stress measurements for roll stand parameters, controller17 uses the numeric values from the incoming stream of data to operateone or more control valves 18 and 18 a in response to a set point valuethat correlates with temperature conditions in mill stand 1 so that themass flow of liquid nitrogen from storage tank 11 to cryogenic coolingdevices 14 a and 14 b is accurately regulated to disperse a controlledcryogen spray or flow onto the work surfaces.

Referring to FIG. 2C, in this embodiment, the cryogen delivery system 10b comprises sensors that are capable of measuring strip profile such asshape and flatness. In this embodiment, the sensors comprise X-ray shapegauges 25 a and 25 b. However, alternate strip profile sensors couldinclude, but are not limited to, tomography gauges, radioisotopetraversing gauges, or shape meters where the strip is pulled at an angleover a segmented roll and the segments include transducers capable ofmeasuring the radial forces exerted on them to provide a signal relatedto strip shape. A wide variety of different devices are available formeasuring strip profile and generating output signals that can be usedto regulate the mass flow of cryogen from storage tank 11 to cryogeniccooling devices 14 a and 14 b. In this instance, gauges 25 a and 25 bgenerate output signals indicative of strip profile and transmit thesignals to controller 17 where the controller 17 calculates numericvalues from the incoming stream of data. When the calculated valuescorrespond to set point values that correlate with mill standtemperature, the controller 17 transmits a signal that operates at leastone control valve 18 so that a desired controlled mass flow of liquidnitrogen from storage tank 11 is transferred to cryogenic coolingdevices 14 a and 14 b. The controlled amount of cryogen dispersed ontothe work surfaces minimizes shape variations in the rolled product andthe relatively constant shape controls mill stand temperature.

In FIG. 2D, the cryogen delivery system 10 b includes at least onesurface roughness gauge 26 a and/or 26 b, for example, a contact gaugeor laser gauge, to measure roughness or texture (Ra) along the rolledproduct 5 surface. As above, the gauges 26 a and 26 b generate outputsignals indicative of the Ra value along the surface of the rolledproduct 5.

Alternatively, a video scanning system, such as surface inspectionsystems offered by Parsytec AG of Aachen, Germany, could be used todetermine roughness. The roughness measurements correlate with thermalconditions and cleanliness of the working rolls existing in a mill stand1, and controller 17 receives the incoming stream of data whereby thecontroller 17 calculates the numeric values, and in response to reachinga set point value, the controller 17 operates control valves 18 and 18 aso that cryogenic cooling devices 14 a and 14 b receive a controlledmass flow of cryogen from storage tank 11 that is dispersed onto thework surfaces in mill stand 1 and keeps the working roll surface clean.

In the embodiment shown in FIG. 2E, stress analyzers 24 a and/or 24 bfirst shown in FIG. 2B are combined with the roughness gauges 26 a and26 b of FIG. 2D to provided cryogen delivery system 10 b having anarrangement of different non-optical sensors to determine differentoperating parameters in the rolled product 5. The different sensorsgenerate their respective output signals that are combined in controller17 and the controller 17 is programmed to calculate numeric values basedon the combined stream of incoming data. When the calculated valuescorrespond with a predetermined set point value, controller 17 transmitsa signal that operates control valves 18 and 18 a so that a desired massflow of cryogen is transmitted from storage tank 11 to cryogenic coolingdevices 14 a and 14 b where the cryogen is dispersed onto the worksurfaces in mill stand 1.

In another set of embodiments, shown in FIGS. 3A through 3C, are variouscryogen delivery systems 10 c having additional different sensorssuitable for measuring operating parameters associated with the cryogendelivered from storage tank 11. Each cryogen delivery system embodiment10 c includes a mill stand 1 having a pair of opposed work rolls 2 a and2 b, a roll gap 3 set to produce a desired cold rolled metallic sheet orrolled product 5, backup rolls 4 a and 4 b, and a strip entry side 6.

Referring in particular to FIG. 3A, the cryogen delivery system 10 cincludes at least one sensor 27 a and/or 27 b, for example, but notlimited to, a thermocouple for measuring condensation 28 in theatmosphere, the condensation created from vapor cooling of humidityproximate the working surfaces receiving cryogen coolant. Sensors 27 aand 27 b generate output signals indicative of the measured condensate,and controller 17 receives the incoming stream of data. When thereceived values correspond with a set point value, controller 17transmits a signal that operates at least one control valve 18 so thatcryogenic cooling devices 14 a and 14 b receive a controlled mass flowof cryogen from storage tank 11 that is dispersed onto the work surfacesin mill stand 1.

In FIG. 3B, the cryogen delivery system 10 c includes at least onecryogenic temperature sensor 29 fitted within conduit 12 to measuretemperature of the cryogen delivered to cryogenic cooling devices 14 aand 14 b. Controller 17 receives the stream of incoming temperaturemeasurements. When the temperature values correspond with a set pointvalue rolling temperature in the mill stand, controller 17 transmits asignal that operates at least one control valve 18 so that cryogeniccooling devices 14 a and 14 b disperse a controlled amount of cryogenonto the work surfaces in mill stand 1.

Referring to FIG. 3C, sensors 27 a and 27 b that monitor thecondensation 28 are combined with the cryogen temperature sensor 29 toprovided cryogen delivery system 10 c having an arrangement of differentsensors to determine different operating parameters associated with thecryogen. The different sensors generate their respective output signalsthat are combined in controller 17, and the controller 17 is programmedto calculate numeric values based on the combined stream of incomingdata. When the calculated values correspond with a predetermined setpoint value, controller 17 transmits a signal that operates at least onecontrol valve 18 so that a desired mass flow of cryogen is transmittedfrom storage tank 11 to cryogenic cooling devices 14 a and 14 b wherethe cryogen is dispersed onto the work surfaces in mill stand 1.

FIG. 4A shows a cryogen delivery system 10 d having sensors formeasuring mill stand parameters in combination with sensors formeasuring rolled product parameters. In this instance, delivery system10 d includes one or more remotely mounted X-ray analyzers 20 a and 20 bas disclosed in FIG. 1B, and at least one surface roughness gauge 26 aand/or 26 b as disclosed in FIG. 2D. However, it should be understoodthat any non-optical sensors capable of measuring mill stand parametersand rolled product parameters can be combined in delivery system 10 dwithout departing from the scope of this invention. The differentsensors generate their respective output signals that are combined incontroller 17, and the controller 17 is programmed to calculate numericvalues from the different streams of incoming data. When the calculatedvalues correspond with a predetermined set point value, controller 17transmits a signal that operates control valves 18 and 18 a so that acontrolled mass flow of cryogen is transmitted from storage tank 11 tocryogenic cooling devices 14 a and 14 b where an accurate amount ofcryogen is dispersed onto the work surfaces in mill stand 1.

FIG. 4B shows a cryogen delivery system 10 e having sensors formeasuring mill stand parameters in combination with sensors formeasuring rolled product parameters, and sensors for measuring cryogenparameters. In this instance, delivery system 10 e includes one or moreremotely mounted X-ray analyzers 20 a and 20 b, as disclosed in FIG. 1B,at least one surface roughness gauge 26 a and/or 26 b as disclosed inFIG. 2D, and at least one cryogenic temperature sensor 29 a, 29 b asdisclosed in FIG. 3B. It should be understood that any non-opticalsensors capable of measuring mill stand parameters, rolled productparameters, and cryogen parameters can be combined in delivery system 10e without departing from the scope of this invention. The differentsensors generate their respective output signals that are combined incontroller 17 and the controller 17 is programmed to calculate numericvalues from the different streams of incoming data. When the calculatedvalues correspond with a predetermined set point value, controller 17transmits a signal that operates control valves 18 and 18 a so that adesired mass flow of cryogen is transmitted from storage tank 11 tocryogenic cooling devices 14 a and 14 b where the cryogen is dispersedonto the work surfaces in mill stand 1.

As such, an invention has been disclosed in terms of preferredembodiments and alternate embodiments thereof, which fulfills each oneof the objects of the present invention as set forth above and providesa method and apparatus for controlling rolling temperature in a coldroll mill stand. Of course, various changes, modifications, andalterations from the teachings of the present invention may becontemplated by those skilled in the art without departing from theintended spirit and scope thereof. It is intended that the presentinvention only be limited by the terms of the appended claims.

1. A method comprising: measuring at least one operating parameter of a cold rolling process, each of the at least one operating parameter being correlated to the thermal conditions of a rolled material of the cold rolling process; and controlling operation of a cryogenic cooling device based at least in part on measurements of the at least one operating parameter.
 2. The method of claim 1, wherein the controlling step comprises setting a cryogenic discharge intensity of the cryogenic cooling device based at least in part on measurements of the at least one operating parameter.
 3. The method of claim 2, further comprising associating a value with each measurement of the at least one operating parameter, wherein the controlling step further comprises adjusting the cryogenic discharge intensity of the cryogenic cooling device to bring the value into a predetermined range if the value falls outside of the predetermined range.
 4. The method of claim 1, wherein the measuring step comprises measuring the at least one operating parameter of the cold rolling process, each of the at least one operating parameter being correlated to the thermal conditions of a surface of the rolled material.
 5. The method of claim 1, wherein the measuring step comprises measuring the at least one operating parameter of the cold rolling process, each of the at least one operating parameter being selected from the group consisting of electrical resistance on a surface of a roll, stress on the surface of the roll, and roughness of the surface of the roll.
 6. The method of claim 1, wherein the measuring step comprises measuring the at least one operating parameter of the cold rolling process, each of the at least one operating parameter being selected from the group consisting of electrical resistance on a surface of a rolled material, stress on the surface of the rolled material, thickness of the rolled material, and flatness of the rolled material.
 7. The method of claim 1, wherein the measuring step comprises measuring a temperature of a rolled material using a non-optical sensor.
 8. The method of claim 1, wherein the controlling step comprises controlling operation of a cryogenic spray device based at least in part on measurements of the at least one operating parameter.
 9. The method of claim 1, wherein the controlling step comprises controlling operation of a cryogenic cooling device based at least in part on averaged numerical values calculated from measurements of the at least one operating parameter.
 10. The method of claim 1, wherein the measuring step comprises continuously measuring at least one operating parameter of the cold rolling process.
 11. An apparatus for use with a cold rolling process, the apparatus comprising: at least one sensor, each of the at least one sensor being adapted to measure an operating parameter of the cold rolling process, the operating parameter being correlated to the thermal conditions of an element of the cold rolling process; a cryogenic cooling device having an adjustable discharge intensity; and a controller that is configured to receive output signals received from the at least one sensor and is programmed to adjust the discharge intensity of the cryogenic cooling device based at least in part on the output signals received from the at least one sensor.
 12. The apparatus of claim 11 wherein the controller is programmed to convert the output signals into values and is programmed to adjust the cryogenic discharge intensity of the cryogenic device to bring the values into a predetermined range if the values fall outside of the predetermined range.
 13. The apparatus of claim 11, wherein the operating parameter is selected from the group consisting of a rolled material and a work roll.
 14. The apparatus of claim 11, wherein the operating parameter is selected from the group consisting of electrical resistance on a surface of a roll, stress on the surface of the roll, and roughness of the surface of the roll.
 15. The apparatus of claim 11, wherein the operating parameter is selected from the group consisting of electrical resistance on a surface of a rolled material, stress on the surface of the rolled material, thickness of the rolled material, and flatness of the rolled material.
 16. The apparatus of claim 11, wherein the operating parameter comprises load force on a work roll used in the cold rolling process.
 17. The apparatus of claim 11, wherein the controller is programmed to calculate average values from the output signals and adjust the discharge intensity of the cryogenic cooling device based at least in part on the average values.
 18. The apparatus of claim 11, wherein the at least one sensor is adapted to continuously measure the operating parameter.
 19. A method comprising: measuring a load force acting on a roll of a cold rolling process; controlling operation of a cryogenic cooling device based at least in part on measurements of the load force.
 20. The method of claim 19, wherein the measuring step comprises measuring a load force acting on a roll of a cold rolling process based on an output signal of at least one load cell. 